1. Field of the Invention
This invention relates generally to telecommunications. More particularly, it relates to public safety.
2. Background of Related Art
There are many handsets that do not register for service with any Commercial Mobile Radio Service (CMRS) carrier. Such handsets are referred to as non-initialized, or non-service initialized (NSI) handsets. Even without a registered CMRS carrier non-initialized handsets are permitted to complete emergency calls to 9-1-1 because there is too great a risk that registration of a legitimate subscriber may fail when roaming onto another carrier's network, and this as a matter of public policy should not prevent the subscriber from placing an emergency call. Moreover, handsets do not register instantly after being powered on, and an emergency call for help should not be delayed while waiting for the completion of registration otherwise necessary for commercial services.
Some handsets may be lost, stolen, thrown away, etc. and may be used by unknown individuals for malicious purposes. Emergency calls to 9-1-1 from these handsets are no longer properly linked to an individual having pre-registered location information, and as such an emergency call made by someone other than the pre-registered person may not be reliably or easily traced to a precise location associated with the current use of the handset. Furthermore, subsequent unknown (to the carrier) individuals making use of a lost, stolen, etc. handset can make numerous anonymous harassing calls to 9-1-1 using these phones, and there is little chance of discovering the identity of the unauthorized individual. Harassing calls to emergency services are made with more frequency than would be thought, and interfere with day-to-day Public Safety operations, posing a risk to legitimate callers and responders.
By the time a harassing emergency call reaches a selective router, the only identification of the initiating handset is the dialed digits (e.g., “911”) followed by a representation of the last seven digits of the phone's electronic ID; this number is sometimes represented as 911-xxx-xxxx. There are only 10 million possible numbers (000-0000 through 999-9999) to differentiate between over an estimated 400 million wireless phones in the U.S. In other words, if electronic identification numbers were evenly distributed, there would be 40 phones that would have the same 911-xxx-xxxx. Because of this, blockage of emergency calls from known harassing handsets is not desirable in the rare (but possible) event that a handset with a different area code (but the same seven digits xxx-xxxx) attempts to make a legitimate emergency call. Plus, some 9-1-1 calls come from handsets that have recently powered up, and not all calls from a particular 911-xxx-xxxx can be blocked indefinitely.
Some solutions have been described from within the carrier networks. Others have attempted to solve the problem from within an E9-1-1 network. None are known to have been implemented.
Exemplary emergency call blocking techniques are described in co-owned U.S. Pat. No. 8,103,242 entitled “E911 Call Blocking For Non-Initialized Wireless Telephones” to Richard Dickinson; U.S. Pat. No. 8,175,570 entitled “E911 Call Blocking For Non-Initialized Wireless Telephones” to Richard Dickinson; and U.S. Pat. No. 8,116,722 entitled “E911 Call Blocking For Non-Initialized Wireless Telephones” to Richard Dickinson.
Disadvantages of the present technologies include the fact that carrier facing solutions require costly changes within carrier networks, and public Safety solutions risk inadvertent blockage of non-offending legitimate emergency callers.